Need advice on skirting below tiled wall

Hello Gentlemen! and ladies (I doubt there r any here)!

Has anyone of u ever applied coving under a tiled wall? Conving with a screed material which has also been used for flooring?

We have come up across a site where there are tiled walls..tile thickness is 10mm. Gap between tile and floor is 10cm. We have to apply skirting with the same material as we have used for flooring (it's a screed). Manufacturer says that the screed is definitely used for skirting too. However, as per manufacturer the whole floor upto walls has been laid first and now we are applying the skirting. The material is costly hence they have fitted a 7mm thick and 9cm wide gypsum board strip on the wall below the tiles to reduce the volume as the material is costly. So we left with filling 3mm of material layer (instead of 10mm). Now because of the nature of material and the method of application (laid whole floor first and then apply skirting) we are facing certain issues like not having a very fine finish at the top edge (where the material meets the tile) and also we are having a thin layer of material on the floor which we have to grind out in order to provide flatness. (The floor and skirting has to be coated too).

I seek advice from you that is it the best and only method which we have applied or there can b other possibilities too? The material being used for flooring is screed Stonhard UT and that for skirting is Stonhard Semstone 5407. I also seek your opinions on these materials as we have been pushed in to use these materials despite of our recommendations for other renowned materials but we are facing many strange issues now due to these materials and their particularly method of application. Has anyone got experience with this Stonhard??